A portable communication device such as a cell phone communicates voice signals over a radio frequency channel via an antenna. The portable communication device incorporates a microphone and a speaker that are used for the voice communication. The portable communication device typically has a housing that includes the microphone and speaker, a display, a key pad, an antenna, and various analog, digital and radio frequency (RF) circuitry that facilitate the reception and transmission of the voice signals over an RF channel. The microphone converts the voice signal into a corresponding electrical signal that is processed by the device circuitry and then modulated for generating a communication signal for transmission via the antenna. The antenna also receives a voice modulated signal that is demodulated in the receiver to produce a voice signal that is applied to the speaker to make the voice signal audible.
The speaker and the microphone are typically disposed in the same housing on opposite ends of the portable communication device. For example, a cell phone is typically held with the speaker being near the user's ear while the user speaks into the microphone. With the miniaturization of electronics, it has now become possible to fit the components of a portable communication device onto a wristband to make a wrist phone. While a wrist phone is more convenient because it is smaller and weighs less, the smaller size can also in some ways be less convenient.
FIG. 1 (prior art) shows a wrist phone 10 attached to a wrist band 11 in which the keypad is implemented on a touch-screen display 12. The space saved by eliminating a physical keypad can be used to enlarge the display 12. Despite the larger virtual keypad, however, the numbers on the keypad are so small that the tip of the user's index finger is larger than a single key. The keys are best pressed using a stylus or the tip of a pen. It is inconvenient for the user to carry the stylus or a pen just to use the touch-screen display 12. In addition, the display is still so small that elderly people have difficulty reading the displayed characters. Moreover, the speaker of the wrist phone cannot be held near the user's ear while the user speaks into the microphone because the length of the wrist phone is typically much shorter than the distance from the user's ear to the user's mouth. Thus, a loudspeaker function is used so that the user can speak into the wrist phone as though the user were reading the time from a wrist watch. The speech quality generated by such a wrist phone is understandably poor as the voice signal output from the loudspeaker enters the microphone disposed in the same small housing. The person talking to the user of the wrist phone hears an echo of that person's own voice.
A method is sought for making a wrist phone that has superior voice quality and for which the user does not have difficulty seeing the display or pressing individual keys of a keypad.